Hi.. Did you gave PowerPrep test? It gives nearly exact score of real test. Also if you have only 2 weeks for your test, practice as many tests as possible. I will recommend to give atleast 2 tests a day till the test date.
I gave my GRE and yes, if you are not prepared mentally, you will blow your test. Just be cool in the test and don't think what will happen, how will be the test, etc.. just think you are giving the test as you did in your home.
I have some good material to refer on the last few days for the test. They are the quantitative formulas with examples, GRE high frequency words, many practice tests, bigbook tests, CAT, word groups to revise on test day, analogies bunch, GRE essay answers, strategies to complete the test and few more.. Will give in few pennies, No freebies pls :D
Best luck for your test!